The world industrial revolution has led to widespread and unrestricted industrial burning of fossil fuels and other combustible materials. For industrial use in steam generators, boilers, furnaces, and the like, such fossil fuels have included hard and soft coal, wood, propane, natural gas, and, sometimes, combinations of these fuels. In addition to the burning of industrial fuels, improvements in incineration techniques and environmental concerns related to the alarming growth of landfills has resulted in the incineration or burning of many other types of materials such as, for example, garbage, tires, medical wastes, used motor oil, paint thinner, and cleaning fluid.
While the burning of fossil fuels and the incineration of waste materials have been important factors in sustaining modern society, such burning also tends to produce immense quantities of harmful by-products that are often simply released directly into the atmosphere. Such by-products can include carbon dioxide, which can contribute to greenhouse warming of the planet and destruction of its protective ozone layer; sulphur and other gases that can cause highly destructive acid rain; lead, mercury, and other toxic metals and metal oxides that can accumulate in the human body; and various fine particulate matter that can precipitate to the ground and harm plants and animals.
For many years, the harmful affects of industrial burning were not recognized and the by-products of such burning were simply belched into the atmosphere in tremendous volumes. More recently, however, a growing world concern for the well being of our planet and its inhabitants has led to a heightened awareness on the part of government and industry of the need to reduce the atmospheric pollution resulting from industrial burning.
Numerous attempts have been made to remove and eliminate harmful elements from industrial smoke before it is released into the atmosphere. Such attempts include filter type scrubbers through which the smoke is passed to remove particulates therefrom, various chemical treatments to render harmful elements within the smoke inert, increasing the actual burning efficiency of the fuels to produce less harmful by-products, and others.
Although these and similar attempts have proven somewhat successful in reducing the volume of harmful materials introduced into the atmosphere, they nevertheless have not been completely successful and, further, tend to be plagued with a number of inherent problems and shortcomings. Filter scrubbers, for example, tend to be very expensive to maintain and operate and can require frequent removal and replacement of the filter elements themselves. Chemical treatments tend to be effective only upon a limited range of harmful elements and can even produce compounds whose affect on the atmosphere are themselves understood only poorly. Also, while improving the efficiency of the actual burning process itself indeed reduces pollutants, unacceptably large amounts of harmful elements still can be introduced into the atmosphere.
Therefore, a persistent and heretofore unaddressed need exists for a method and apparatus adapted to remove a wide range of harmful elements from industrial smoke streams reliably, efficiently, and economically without producing harmful by-products of its own. It is to the provision of such a method and apparatus that the present invention is primarily directed.